Question: $\begin{aligned}&\phantom{{\times}}4\\ \\ &\underline{\times5}\\ \\ \end{aligned}$ $~~$
Solution: We can think of ${4} \times {5}$ as $4$ rows of $5$ circles. How many circles are there? ${1}$ ${2}$ ${3}$ ${4}$ ${5}$ ${4}$ ${\color{#AA87FF}{1}}$ ${\color{#AA87FF}{2}}$ ${\color{#AA87FF}{3}}$ ${\color{#AA87FF}{4}}$ ${\color{#AA87FF}{5}}$ ${3}$ ${\color{#AA87FF}{6}}$ ${\color{#AA87FF}{7}}$ ${\color{#AA87FF}{8}}$ ${\color{#AA87FF}{9}}$ ${\color{#AA87FF}{10}}$ ${2}$ ${\color{#AA87FF}{11}}$ ${\color{#AA87FF}{12}}$ ${\color{#AA87FF}{13}}$ ${\color{#AA87FF}{14}}$ ${\color{#AA87FF}{15}}$ ${1}$ ${\color{#AA87FF}{16}}$ ${\color{#AA87FF}{17}}$ ${\color{#AA87FF}{18}}$ ${\color{#AA87FF}{19}}$ ${\color{#AA87FF}{20}}$ $\begin{aligned}&\phantom{{\times}}4\\ \\ &\underline{\times5}\\ \\ &~~C{20} \end{aligned}$